Problem: Multiply. $3.4 \times 6.1 = $
Answer: $34 \times 61$ and $3.4 \times 6.1$ multiply the same digits in the same order. So, the product of both problems will also have the same digits in the same order. Let's multiply $34 \times 61$. Then we can estimate to place the decimal point in the product of $3.4 \times 6.1$. $\begin{aligned} 34&\\ \underline{ \times 61}&\\ 4}\\ 30}\\ 240}\\ \underline{+1{,}800}}\\ 2{,}074 \end{aligned}$ Let's estimate to place the decimal in $3.4 \times 6.1$. $\begin{aligned} 3.4 \times 6.1 &\approx 3 \times 6\\\\ &\approx 18 \end{aligned}$ Where can we place the decimal in $2074$ to get a product close to $18$ ? $3.4 \times 6.1 = 20.74$